1. Field of the Invention
The invention relates to a method of routing in an ad hoc network that differentiates critical applications and optimizes resources according to the expected quality of service.
The flow of multimedia streams through an ad hoc network comprising mobile nodes interconnected by radio means leads to the selection and maintenance of routes that are compatible with end-to-end quality of service despite variations in topology that are difficult to predict.
The networks concerned are, for example, extensive networks used to convey voice and data services without having to rely on a rigid structure up to the capillary level. The resources needed for the flow of these streams as well as the signaling systems (resource management and routing systems) must be minimized and used as a priority for operationally important services such as telephony services or emergency messaging.
2. Description of the Prior Art
In the field of ad hoc network routing and extensions for QoS, the prior art deals with the following goals:                providing the best route, namely the shortest route in number of hops, and minimizing the exchanges of routing signals. These methods, however, are not sufficient to meet the needs of multimedia communications. Quality of service is not taken into account.        discovering the routes that respond to quality of service (QoS) criteria. The methods associated do not enable the efficient processing of the route requests in extensive networks, because they limit themselves to proposing exceptional QoS processing mechanisms, whence a loss of efficiency of the basic routing protocol.        offering a routing algorithm that takes account of the quality of service QoS by which it is possible to control the volume of signaling packets, even when the size of the network grows. These methods have the flaw wherein they introduce a narrow coupling between bandwidth reservation and routing, which means that it is not possible to simply process all the QoS elements in a radio network. Most of these elements, namely the error rate, the safety level, the level of consumable energy, the jitter and the time lag have no relation with bandwidth reservation or with the criteria of the emergency requests.        taking account of the longevity of the routes, the energy consumed during relaying operations or any other criterion. These methods are optimized according to one metric alone, and this does not provide a comprehensive solution.        partitioning a network into Virtual Service Networks (VSN) using predetermined characteristics. These methods are not directly applicable to an ad hoc radio network in which the capacities of the links are variable as a function of random factors related to propagation and position of the nodes.        modeling the ad hoc network in terms of hyperlinks and taking account of the states of mobile nodes. These methods are not directly applicable to a very extensive network that emphasizes multiple multipoint links, access techniques (e.g.: TDMA) or adaptive antennas.        
In short, the prior art describes many techniques that tend to support multimedia communications in radio networks using ad hoc organization, but the metric multiples to be taken into account are such that the problem to be resolved remains without any satisfactory solution, in terms of both service rendered and optimization of means.